With a 4mm offset, articulated midsole and toothy microlug outsole, the FluidFlex™ guarantees a close-to-ground feel that both flexes with the natural movement of your foot, and protects it at the same time.

The FluidFlex opens an entirely new class of shoe. It is comfortable and cushioned underfoot but runs with the responsiveness and snap of a racing flat. The low drop and sleek profile, along with light weight give it the feel of quickness that we often associate with more minimal shoes. However, the innovative cushioning system keeps your feet and legs from taking a beating. This is my go to shoe this summer for all races up to 50 miles and training. I haven't yet taken it over that distance but it even be the first lightweight shoe that I would be comfortable with in a 100 miler.

For a while now, I've been running in shoes with a 4mm heel drop. I wear Montrail Rogue Racers casually, because the truly neutral fit feels great on my foot, but it was always too much heel for me to run trail in. In the meantime, I've patiently waited for Montrail to come out with a minimalist shoe in the 4mm-6mm range. It's finally here, and it does not disappoint.

I've only put about 25 miles on these so far, but I'm in love. The only other shoes I know of that pair a good amount of cushioning with a 4mm drop are the Brooks PureGrit & PureFlow -- I also own a pair of the latter -- but this "FluidFoam" cushioning feels more resilient to me, and the upper of the FluidFlex is much more breathable. The extra cushioning makes for a slightly higher stack height than some other minimalist running shoes, but the 4mm differential keeps the foot stride natural and healthy.

I also prefer the tread pattern on the Montrails, with little square nubbins like on the Rogue Racer and Bajada. These offer a great balance between traction on mud/loose dirt and traction on slick rock, roots, etc. There isn't really much to the upper at all, and I have to keep them laced pretty tightly to keep things locked down, but the asymmetrical lacing keeps me chafe-proof no matter how tight I go.

Beyond that, two things stand out a little bit about this shoe. First, the heel cup is very deep, with two little pads to hold your heel in place. This works really well, although it looks a little weird, but I do have to wear a taller sock (Smartwool mini instead of micro) in order to prevent the top of the heel from rubbing my achilles. Second, there is a section of exposed foam in the middle of the outsole that I thought might be a durability issue -- but other than collecting some mud, it doesn't seem to be any worse for wear after a couple of decent runs.

The verdict? These are my favorite Montrail trail running shoes to date. For those who want a truly neutral shoe without any of the stupid contouring and "support" that other manufacturers seem to insist on building into their minimal shoes, and for those who want natural geometry without being forced to forego cushioning entirely, this is your new running shoe.